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Thread: Weird CH test behavior

  1. Back To Top    #1

    Join Date
    Aug 2010
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    Weird CH test behavior

    My CH customarily reads around 280, including a test weekend before last. Then this past weekend, armed with my new speedstir, I tested it again. But the sample never turned blue! Instead, around the normal endpoint, it turned CLEAR. Not even a tinge of any color I could discern. Added more drops up to 50, with no additional change.

    Thinking that maybe the speedstir was responsible (specifically that I hadn't rinsed the bar sufficiently between tests) I proceeded to retest manually, with the same results - solution turns clear, no blue endpoint at all.

    The reagents are about a year old, and have been stored inside, in a dark cool closet. The 0011L is not staining its bottle so seems to still be good. There's never been any indication that I have metals, though I haven't specifically gotten that tested. (The water quality here is sufficiently high that I'd be astounded if there was any notable metal content in the fill water, and I've never used any Cu-containing algaecides or anything. And certainly nothing's changed in that regard since the last normal test.)

    Has anybody ever seen this before? Any ideas what's up?
    20k gallon IGP
    Plaster over gunite
    3/4 hp Hayward pump
    Purex Triton DE filter
    TF100 test kit w/ speedstir

  2. Back To Top    #2
    Richard320's Avatar
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    Re: Weird CH test behavior

    If you have real high FC, it can mess with the colors. I've seen it more with the TA test, personally.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    Mod Squad Bama Rambler's Avatar
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    Re: Weird CH test behavior

    You can try the fading endpoint fix as listed in the Extended Test Kit Directions. That may help.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    JasonLion's Avatar
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    Re: Weird CH test behavior

    Very high FC levels can cause that effect.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  5. Back To Top    #5

    Join Date
    Aug 2010
    Location
    Boston, MA
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    Re: Weird CH test behavior

    FC was 10.0. Would that be high enough? I'd have sworn I've done the test several times at levels higher than that.
    20k gallon IGP
    Plaster over gunite
    3/4 hp Hayward pump
    Purex Triton DE filter
    TF100 test kit w/ speedstir

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